The diurnal periodicity of hexose transporter mRNA and protein levels in the rat jejunum: Role of vagal innervation

Houghton, Scott G.; Zarroug, Abdalla E.; Duenes, Judith A.; Fernández-Zapico, Martín E.; Sarr, Michael G.

doi:10.1016/j.surg.2005.09.002

Cited by 36 publications

(36 citation statements)

References 27 publications

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“…[1][2][3][4][5][6][7][8]10 In agreement with these reports, we demonstrated that the diurnal rhythms in hexose transporter mRNA and protein levels in proximal bowel appear to be entrained by or are at least associated with the nocturnal feeding behavior of rats. Studies of transporter-mediated glucose uptake studies correlated with the nocturnal feeding behavior of rats showing maximal uptake during the dark cycle; this has been shown previously for SGLT1.…”

Section: Discussionsupporting

confidence: 91%

“…These variations could also be explained by post-transcriptional or posttranslational mechanisms which could also account for the variable time interval reported between peaks in mRNA and protein expression in diurnal studies, even by our own group. 2 We observed the expected diurnal rhythms in transporter-mediated glucose uptake throughout the length of the small bowel with diurnal rhythms present in proximal bowel but absent in ileum. In addition, overall absorptive capacity was greater in duodenum and jejunum compared to ileum.…”

Section: Discussionmentioning

confidence: 62%

“…The lack of a diurnal rhythm in ileal protein levels of SGLT1 and GLUT2 could be a consequence of the method used to measure protein levels. 2 We used semi-quantitative Western blotting, which is likely not as sensitive for detecting changes in protein levels as realtime PCR is in detecting changes in levels of mRNA. Nevertheless, the lack of a diurnal rhythm in transporter-mediated glucose uptake in ileum supports the absence of changes in protein levels.…”

Section: Discussionmentioning

confidence: 99%

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Coordinated, diurnal hexose transporter expression in rat small bowel: Implications for small bowel resection

Houghton

Iqbal

Duenes

et al. 2008

Surgery

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

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Coordinated, diurnal hexose transporter expression in rat small bowel: Implications for small bowel resection

Houghton

Iqbal

Duenes

et al. 2008

Surgery

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“…The nature of this nutrient signaling pathway remains unclear: candidates for afferent and/or efferent components include peptide hormones (systemic or paracrine), neuronal communication, and luminal sensors. Studies on the role of the vagus nerve have yielded contradictory results (16,36).In this study, we sought to clarify the mechanism and effect of vagotomy on SGLT1 expression. In particular, the role of afferent vagal pathways using capsaicin will allow specific testing of the contribution of these fibers.…”

mentioning

confidence: 99%

Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na⁺/glucose cotransporter SGLT1

Stearns¹,

Balakrishnan²,

Rounds³

et al. 2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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Stearns AT, Balakrishnan A, Rounds J, Rhoads DB, Ashley SW, Tavakkolizadeh A. Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na ϩ /glucose cotransporter SGLT1. Am J Physiol Gastrointest Liver Physiol 294: G1078-G1083, 2008. First published February 28, 2008 doi:10.1152/ajpgi.00591.2007.-Introduction: the intestinal Na ϩ /glucose cotransporter (SGLT1) displays rapid anticipatory diurnal rhythms in mRNA and protein expression. The vagus nerve has been implicated in the entrainment of some transporters. We aimed to clarify the influence of the vagus nerve on the diurnal entrainment pathway for SGLT1 and examine the role of vagal afferent fibers. Methods: male Sprague-Dawley rats were randomized to three groups, total subdiaphragmatic vagotomy, selective deafferentation of the vagus with capsaicin, or sham laparotomy. Postoperatively, animals were maintained in a 12-h light-dark cycle with food access limited to night. On the ninth postoperative day, animals were euthanized to harvest jejunal mucosa at 6-h intervals starting at 10 AM. Whole cell SGLT1 protein was measured by semiquantitative densitometry of immunoblots. Sglt1 and regulatory subunit RS1 mRNA was assessed by quantitative PCR. Fluorogold tracer technique was used to confirm adequacy of the vagotomy. Results: the diurnal rhythm in intestinal SGLT1, with a 5.3-fold increase in Sglt1 mRNA at 4 PM, was preserved in both vagotomy and capsaicin groups. However, the rhythmicity in SGLT1 protein expression (2.3-fold peak at 10 PM; P ϭ 0.041) was abolished following either total vagotomy or deafferentation. Lack of change in RS1 mRNA suggests this is independent of the RS1 regulatory pathway. Conclusion: SGLT1 transcription is independent of the vagus. However, dissociation of the protein rhythm from the underlying mRNA signal by vagotomy suggests the vagus may be involved in posttranscriptional regulation of SGLT1 in an RS1 independent pathway. Disruption following afferent ablation by capsaicin suggests this limb is specifically necessary. glucose transport; vagus; vagotomy THE APICAL na ϩ /glucose cotransporter (SGLT1), localized on the brush-border membrane of small bowel enterocytes, is responsible for all secondary active absorption of glucose from the small bowel (14,19). Dysregulation of SGLT1 is increasingly recognized in type 2 diabetes mellitus, with expression increasing up to fourfold in both patients and animal models (4, 7-9). Similarly, knockout of the SGLT1 regulatory subunit protein RS1 in mice leads to both SGLT1 overexpression and severe obesity (27). Therapy aimed at modulating SGLT1 expression may therefore have clinical benefits in diabetes and obesity through slowing of glucose absorption in a manner similar to amylase inhibitors (5) and through increased ileal glucose delivery (38). SGLT1 expression is regulated by several inputs, including diet composition (11) and the timing of food intake (28). Despite significant progress in characterizing the physiological signaling mechanisms regulating SGL...

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“…Rats were kept on a warmed mat to avoid inducing hypothermia during the perfusion. We studied jejunal glucose uptake in Lewis rats between 8:00-11:00 a.m. Adherence to this schedule was undertaken to avoid the known diurnal patterns in hexose transporter expression and function which would confound our results [19].…”

Section: Designmentioning

confidence: 99%

Acute Enterocyte Adaptation to Luminal Glucose: A Posttranslational Mechanism for Rapid Apical Recruitment of the Transporter GLUT2

Chaudhry¹,

Scow²,

Madhavan³

et al. 2011

Gastroenterology

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The diurnal periodicity of hexose transporter mRNA and protein levels in the rat jejunum: Role of vagal innervation

Cited by 36 publications

References 27 publications

Coordinated, diurnal hexose transporter expression in rat small bowel: Implications for small bowel resection

Coordinated, diurnal hexose transporter expression in rat small bowel: Implications for small bowel resection

Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na⁺/glucose cotransporter SGLT1

Acute Enterocyte Adaptation to Luminal Glucose: A Posttranslational Mechanism for Rapid Apical Recruitment of the Transporter GLUT2

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The diurnal periodicity of hexose transporter mRNA and protein levels in the rat jejunum: Role of vagal innervation

Cited by 36 publications

References 27 publications

Coordinated, diurnal hexose transporter expression in rat small bowel: Implications for small bowel resection

Coordinated, diurnal hexose transporter expression in rat small bowel: Implications for small bowel resection

Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na+/glucose cotransporter SGLT1

Acute Enterocyte Adaptation to Luminal Glucose: A Posttranslational Mechanism for Rapid Apical Recruitment of the Transporter GLUT2

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Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na⁺/glucose cotransporter SGLT1